wrote:
Radium should not be considered as glow in the dark since it actually
gives out light and is radioactive. Do light bulbs glow in the dark?

I don't know why that shouldn't be "glow in the dark", it's what the
purpose of using radium salts in paints was all for.

Purified radium does show some luminescence, but it's pretty low level
comparatively and would require far more material by itself. The
radiation emitted by radium can also cause certain materials, called
"phosphors" to emit light. It was mixtures of radium salts and
appropriate phosphors which were widely used for clock dials and gauges
before the risks of radium exposure were understood.

Glow in the dark materials are those that absorb surrounding light and
give out this light through a glow. This process is similar to
photosynthesis and is what today's glow is all about.

http://www.glowinfo.com/

Their products are actually one of three processes -- chemical reaction
yielding light, uv-light reactive phosporesence, and the visible-light
reactive photo-luminesence. The latter isn't to be confused w/
photosynthesis.

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